Ubiquitous network access has been almost realized today. From network infrastructure point of view, different networks belong to different layers (e.g., distribution layer, cellular layer, hot spot layer, personal network layer, and fixed/wired layer) that provide different levels of coverage and connectivity to users. Because the coverage of a specific network may not be available everywhere, and because different networks may be optimized for different services, it is thus desirable that user devices support multiple radio access networks on the same device platform. As the demand for wireless communication continues to increase, wireless communication devices such as cellular telephones, personal digital assistants (PDAs), smart handheld devices, laptop computers, tablet computers, etc., are increasingly being equipped with multiple radio transceivers. A multiple radio terminal (MRT) may simultaneously include a Long-Term Evolution (LTE) or LTE-Advanced (LTE-A) radio, a Wireless Local Area Network (WLAN, e.g., WiFi) access radio, a Bluetooth (BT) radio, and a Global Navigation Satellite System (GNSS) radio.
Due to spectrum regulation, different technologies may operate in overlapping or adjacent radio spectrums. For example, LTE/LTE-A TDD mode often operates at 2.3-2.4 GHz, WiFi often operates at 2.400-2.483.5 GHz, and BT often operates at 2.402-2.480 GHz. Simultaneous operation of multiple radios co-located on the same physical device, therefore, can suffer significant degradation including significant coexistence interference between them because of the overlapping or adjacent radio spectrums. Due to physical proximity and radio power leakage, when the transmission of data for a first radio transceiver overlaps with the reception of data for a second radio transceiver in time domain, the second radio transceiver reception can suffer due to interference from the first radio transceiver transmission. Likewise, data transmission of the second radio transceiver can interfere with data reception of the first radio transceiver.
Various in-device coexistence (IDC) interference mitigation solutions have been proposed. For example, an UE may request network assistance to mitigate IDC interference via frequency division multiplexing (FDM), time division multiplexing (TDM), and/or power management principles. While the various FDM, TDM, and power management solutions may solve some of the IDC interference problems, there are still remaining issues. For example, the UE will report unusable frequencies to eNB for FDM solutions. However, it is not yet clear that how the unusable frequencies are judged and in which format it will be reported to eNB. It is also not clear that how the unusable frequencies are reported. Can the report of unusable frequencies be used along with reactive or proactive trigger? Can the report of unusable frequency resolve ping-pong effect? In addition, how does the UE detect IDC interference problem, and can such detection be managed by eNB? A systematic approach is necessary to resolve above problems together.